The invention relates to wiring ducts, or wireways, for the reception of bundles of electrical conductors for use in control panels and electrical cabinets. Such wiring ducts are used for holding, supporting and retaining electrical conductors in an orderly manner within a channel, and for permitting individual electrical conductors to be routed from the channel to electrical elements which are interconnected by means of the conductors.
In electrical equipment wherein a plurality of electrical conductors or wires are used for interconnecting diverse elements of the equipment, such as control panels and cabinets for machine tools, welders, electrochemical machining machines, electrical discharge machining, etc., it is desirable to obtain a neat routing of the interconnecting electrical conductors. The problem is often complicated in view of the small space available, the multitude of conductors, and the plurality of varied elements interconnected. The diverse electrical conductors may be placed in juxtaposition in a bundle or harness arrangement as a result of lacing together a plurality of conductors, the bundles or harnesses being attached to a supporting panel by appropriate means. However, it has become a generally accepted procedure in the field, for the sake of neatness and safety, and for the ease of repair which may require replacement of some of the electrical elements, to route bundles of conductors through one or several wiring ducts or wireways, each generally in the form of a U-shaped channel which is cut to appropriate length to fit the installation. Such U-shaped channels are sometimes made of stamped metal or metallic grillwork, but generally they are made of a flexible plastic material or the like. They are attached to the panel or other support means by way of conventional fasteners, such as screws and the like, passed through appropriate mounting holes disposed in the base of the channels, or they are held in position by means of clips or like means. The many electrical conductors required for the installation are routed between elements through such ducts and they are usually held within such ducts by means of a snap-on cover. The ducts are provided with apertures permitting the individual conductors from the bundle to be routed into or from the duct for connection to appropriate electrical elements at various locations. Such apertures may be in the form of a plurality of circular holes, as shown in U.S. Pat. Nos. 3,126,444 and 2,867,681, or they may be in the form of parallel sided slits, as disclosed in U.S. Pat. Nos. 3,156,756, 3,229,029, 2,921,607 or they may be in the form of spaces between the elements of a grillwork as disclosed in U.S. Pat. No. 3,024,301, for example, the slits being sometimes open to the edge of the sidewall in which they are disposed preferably by way of a restricted passage, such restricted passage permitting the individual conductors to be routed through the sidewalls by snapping through the passageway into the slit, while closed slits and other apertures require the wire end to be threaded through the aperture.
The present invention contemplates a wiring duct or wireway, generally U-shaped in cross section and provided with a plurality of slits in at least one sidewall thereof. The slits are of the open variety, that is they are open to the edge of the sidewall, and each slit is provided with diverging sides from the bottom or base portion of the channel to the edge of the sidewall, terminating at the edge itself with a restricted gap portion so as to normally hold in each slit a plurality, if so required, of conductors routed through the sidewall of the duct. The remaining portions of the sidewall between consecutive slits form substantially flexible separate finger-like members having an enlarged free end proximate the edge of the sidewall. The finger-like members have a width proximate the bottom or base portion of the channel which is greater than the width of the finger-like members proximate their enlarged free end near the edge of the sidewall.
Such a structure provides an increased area of open slit for a multitude of electrical conductors to pass through the sidewall at a given slit position, while not reducing the strength of the sidewall portions remaining after the slits have been punched out and which define the finger-like members, especially at the root of each finger-like member integral with the remaining of the sidewall, which is thus proportionally widened according to the amount of divergence of the slit sides. A further advantage of the construction of the present invention is to provide a greatly increased open area at the portion of the slit proximate the edge of the sidewall where the majority of connecting wires or conductors are generally routed for attachment to electrical elements having terminals generally disposed a certain distance away from the surface on which the elements are mounted. Furthermore, the construction of the present invention provides finger-like members formed by the remaining portions of the sidewall between consecutive slits which are substantially stiff, where so desirable, i.e. at the root where they are made integral with the remaining portion of the sidewall proximate the base of the duct, and having a narrower body portion proximate the edge of the sidewall where stiffness of the finger-like members becomes less important. Because of the increased area resulting from forming in the sidewall slits having divergent and non-parallel sides, there is less material remaining in the finished duct than is the case in conventional construction, with the result that the duct is substantially lighter than a conventional duct, without any sacrifice as to rigidity and sturdiness, and the material punched out from the slits is not entirely lost as it can be remelted and reused for extrusion of further ducts or other products.
It is significant that the finished channel according to the present invention includes spaced fingers which by reason of the teachings of the invention provide a plurality of wedge surfaces at the bottom and at the upper corners of the slits. This provides a solid holding arrangement for retaining certain of the wires near the open end of the slit against lateral displacement out of the open end. At the same time, wires retained in place at the bottom of the slit are held in place from vertical displacement by a like wedge effect. This is important when wires are being threaded in the channel before the locking cover has been clamped in place.